Manual Transmission for Vehicles

ABSTRACT

A manual transmission for vehicles minimizes rotational inertia and improves rattle as a consequence of preventing unnecessary idling of a first speed gear and a reverse speed gear by maintaining a first input gear to be a free gear state at all shift-speeds except a first forward speed and a reverse speed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2010-0123022 filed Dec. 3, 2010, the entire contentsof which application is incorporated herein for all purposes by thisreference.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a manual transmission for vehicles.More particularly, the present invention relates to a manualtransmission for vehicles that minimizes rotational inertia and improvesrattle as a consequence of preventing unnecessary idling of a firstspeed gear and a reverse speed gear by maintaining a first input gear tobe a free gear state at all shift-speeds except a first forward speedand a reverse speed.

2. Description of Related Art

Generally, vibration is generated by impact when teeth of free gearsdisposed on rotation shafts freely bumps into driving gears fixedlydisposed on the rotation shafts. A rattle in a manual transmission forvehicles means that the vibration generated by the impact is transmittedto the rotation shafts, bearings, and a transmission case and noiseoccurs.

If load is not applied to a free gear FG, teeth of the free gear FG isnot engaged with both teeth of a driving gear DG as shown in FIG. 1. Atthis state, if load (exciting force of an engine) is applied to the freegear FG, the free gear FG moves easily and the teeth of the free gear FGbumps into the teeth of the driving gear DG. Therefore, double sideimpact occurs, and thereby the rattle occurs.

When the rattle occurs, the double side impact which the free gear FGapplies to the rotation shaft is proportional to rotational inertia ofthe free gear FG, and rattle sensitivity is proportional to totalrotational inertia of the free gears.

Gear arrangement of a conventional manual transmission will bedescribed. As shown in FIG. 2, gears that are related to eachshift-speed are disposed on an input shaft PIS and an output shaft POSdisposed in parallel with the input shaft PIS with a predetermineddistance.

A first input gear GI1, a second input gear GI2, a first synchronizermechanism PSYN1 including third and fourth input gears GI3 and GI4, anda second synchronizer mechanism PSYN2 including fifth and sixth inputgears GI5 and GI6 are sequentially disposed on the input shaft PIS froma front side to a rear side.

Herein, the front side means a side close to an engine and the rear sidemeans a side that is far from the engine.

The first input gear GI1 and the second input gear GI2 are integrallyformed with the input shaft PIS so as to rotate together with the inputshaft PIS when the input shaft PIS rotates.

In addition, the third, fourth, fifth, and sixth input gears GI3, GI4,GI5, and GI6 are disposed such that rotations of the third, fourth,fifth, and sixth input gears GI3, GI4, GI5, and GI6 are not directlyaffected by rotation of the input shaft IS (that is, free gear), andeach input gear GI3, GI4, GI5, and GI6 rotates together with the inputshaft PIS through selective engagement with sleeves PS1 and PS2.

In addition, a first output gear POG1, a third synchronizer mechanismPSYN3 having first and second speed gears GO1 and GO2 engagedrespectively to the first and second input gears GI1 and GI2, and third,fourth, fifth, and sixth speed gears GO3, GO4, GO5, and GO6 engagedrespectively to the third, fourth, fifth, and sixth input gears GI3,GI4, GI5, and GI6 are disposed on the output shaft POS.

The first and second speed gears GO1 and GO2 are disposed such thatrotations of the first and second speed gears GO1 and GO2 do notdirectly affect on rotation of the output shaft POS (that is, freegear), and rotate together with the output shaft POS through selectiveengagement with a sleeve PS3. The third, fourth, fifth, and sixth speedgears GO3, GO4, GO5, and GO6 are integrally formed with the output shaftPOS.

In addition, a second output gear POG2 and a fourth synchronizermechanism PSYN4 having a reverse speed gear PRG engaged to the firstspeed gear GO1 are disposed on a reverse speed output shaft PRS disposedin parallel with the input shaft PIS.

The reverse speed gear PRG is disposed such that rotation of the reversespeed gear PRG does not directly affect on rotation of the reverse speedoutput shaft PRS, and rotates together with the reverse speed outputshaft PRS through selective engagement with a sleeve PS4.

In addition, the first and second output gears POG1 and POG2, as shownin FIG. 3, are engaged to driven gear PDG of a differential so as tooutput converted torque.

Since the first, second, third, and fourth synchronizer mechanismsPSYN1, PSYN2, PSYN3, and PSYN4 are the same as or similar to aconventional synchronizer mechanism applied to a conventional manualtransmission, detailed description thereof will be omitted. In addition,each sleeve PS1, PS2, PS3, and PS4 of the first, second, third, andfourth synchronizer mechanisms PSYN1 PSYN2, PSYN3, and PSYN4, as wellknown to a person of skilled in the art, is operated by a shift forkthat is operated by a shift lever disposed at a driver's seat.

Since the reverse speed gear PRG is always engaged with the first speedgear GO1 and the first speed gear GO1 is always engaged with the firstinput gear GI1 in the manual transmission as shown in FIG. 3, thereverse speed gear PRG and the first speed gear GO1 are idling atshift-speeds other than a first forward speed and a reverse speed andrattle occurs if the input shaft PIS rotates.

The information disclosed in this Background section is only forenhancement of understanding of the general background of the inventionand should not be taken as an acknowledgement or any form of suggestionthat this information forms the prior art already known to a personskilled in the art.

SUMMARY OF INVENTION

Various aspects of the present invention provide for a manualtransmission for vehicles having advantages of minimizing rotationalinertia and improving rattle as a consequence of preventing unnecessaryidling of a first speed gear and a reverse speed gear by maintaining afirst input gear to be a free gear state at all shift-speeds other thana first forward speed and a reverse speed.

One aspect of the present invention is directed to a manual transmissionfor vehicles that may include an input shaft having first, second,third, fourth, fifth, and sixth input gears disposed thereon, an outputshaft disposed in parallel with the input shaft with a predetermineddistance and having a first output gear and first, second, third,fourth, fifth, and sixth speed gears disposed thereon, the first,second, third, fourth, fifth, and sixth speed gears being respectivelyengaged with the first, second, third, fourth, fifth, and sixth inputgears, and a reverse speed output shaft disposed in parallel with theoutput shaft with a predetermined distance and having a second outputgear and a reverse speed gear disposed thereon, the reverse speed gearbeing engaged with the first speed gear, wherein the first input gear isselectively connected to the input shaft by a first synchronizermechanism, the second input gear is integrally formed with the inputshaft, the third and fourth input gears are selectively connected to theinput shaft by a second synchronizer mechanism, the fifth and sixthinput gears are selectively connected to the input shaft by a thirdsynchronizer mechanism, the first and second speed gears are selectivelyconnected to the output shaft by a fourth synchronizer mechanism, thethird, fourth, fifth, and sixth speed gears are integrally formed withthe output shaft, and the reverse speed gear is selectively connected tothe reverse speed output shaft by a fifth synchronizer mechanism.

The manual transmission may further include a first shift rail operatingthe fifth synchronizer mechanism, a second shift rail operating thefirst synchronizer mechanism, a third shift rail operating the fourthsynchronizer mechanism, a fourth shift rail operating the secondsynchronizer mechanism, and a fifth shift rail operating the thirdsynchronizer mechanism.

The first, second, third, fourth, and fifth shift rails may besequentially disposed.

The first, third, fourth, and fifth shift rails may be respectivelyprovided with a shift lug for moving a corresponding shift rail.

The manual transmission may further include a synchronizer operatingdevice moving the second shift rail by a movement of the first shiftrail or the third shift rail.

The synchronizer operating device may include a first rotation linkconnecting the first shift rail with the second shift rail and movingthe second shift rail to an opposite direction of a moving direction ofthe first shift rail when the fifth synchronizer mechanism is operated,and a second rotation link connecting the second shift rail with thethird shift rail and moving the second shift rail to an oppositedirection of a moving direction of the third shift rail when the fourthsynchronizer mechanism is operated.

The synchronizer operating device may further include an elastic membersupplying elastic force for returning the second shift rail moved by themovement of the first shift rail or the third shift rail to an originalposition.

The second rotation link may be adapted to move the second shift rail ina case the third shift rail moves to one direction and not to move thesecond shift rail in a case that the third shift rail moves to the otherdirection.

The first rotation link may be configured that the movement of the thirdshift rail is not affected by the movement of the first shift rail.

The second rotation link may be configured that the movement of thefirst shift rail is not affected by the movement of the third shiftrail.

In a manual transmission according to various embodiments of the presentinvention, a first input gear on an input shaft may be engaged with afirst speed gear on an output shaft and a reverse speed gear on areverse speed output shaft may be engaged with the first speed gear. Thefirst input gear may be selectively connected to the input shaft by afirst synchronizer mechanism. The manual transmission may furtherinclude a synchronizer operating device that operates the firstsynchronizer mechanism by operations of a fourth synchronizer mechanismand a fifth synchronizer mechanism.

The synchronizer operating device may further include a first rotationlink interposed between a first shift rail for operating the fifthsynchronizer mechanism and a second shift rail for operating the firstsynchronizer mechanism and adapted to push the second shift rail to anopposite direction of a moving direction of the first shift rail, asecond rotation link interposed between a third shift rail for operatingthe fourth synchronizer mechanism and the second shift rail foroperating the first synchronizer mechanism and adapted to push thesecond shift rail to an opposite direction of a moving direction of thethird shift rail, and an elastic member supplying elastic force to thesecond shift rail to an original position.

The first rotation link may have both end portions and a middle portion.The middle portion may be hinged to a transmission housing, the one endportion may have a slot having a predetermined length along a lengthdirection thereof such that a hinge protrusion fixed to the first shiftrail is slidably inserted in the slot, and the other end portion mayhave a side that is cut and the other side formed of a supportingportion for supporting a protrusion fixed to the second shift rail.

The second rotation link may have both end portions and a middleportion. The middle portion may be hinged to the transmission housing,the one end portion may have a side that is cut and the other sideformed of a supporting portion for supporting a protrusion fixed to thesecond shift rail, and the other end portion may have a slot having apredetermined length along a length direction thereof such that a hingeprotrusion fixed to the third shift rail is slidably inserted in theslot.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram for explaining occurrence of rattle.

FIG. 2 is a schematic diagram of a conventional manual transmission.

FIG. 3 is a schematic diagram for showing engagement of gears related toa reverse speed in a conventional manual transmission.

FIG. 4 is a schematic diagram of an exemplary manual transmissionaccording to the present invention.

FIG. 5 is a schematic diagram of an exemplary shift rail and anexemplary synchronizer operating device applied to various embodimentsof the present invention.

FIG. 6 is a front view of FIG. 5.

FIG. 7 is a rear view of FIG. 5.

FIG. 8 is an operational diagram of an exemplary synchronizer mechanismat a first forward speed according to the present invention.

FIG. 9 is an operational diagram of an exemplary synchronizer mechanismat a reverse speed according to the present invention.

FIG. 10 is an operational diagram of an exemplary synchronizer mechanismat a second forward speed according to the present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims.

Description of components that are not necessary for explaining thepresent invention will be omitted, and the same constituent elements aredenoted by the same reference numerals in this specification.

FIG. 4 is a schematic diagram of a manual transmission according tovarious embodiments of the present invention. In the drawings, ISrepresents an input shaft, OS represents an output shaft, and RSrepresents a reverse speed output shaft.

Rotation shafts IS, OS, and RS are rotatably mounted at a transmissioncase by interposing rolling elements therebetween, and are disposed inparallel with each other with predetermined distances.

First, second, third, fourth, fifth, and sixth input gears DI1, DI2,DI3, DI4, DI5, and DI6 are sequentially disposed on the input shaft ISfrom a front side to a rear side.

Herein, the front side means a side close to an engine and the rear sidemeans a side that is far from the engine.

In addition, the first input gear DI1 is disposed so as not to bedirectly affected by rotation of the input shaft IS (free gear) and isselectively connected to the input shaft IS through a first synchronizermechanism SYN1. The second input gear DI2 is integrally formed, and maybe monolithically formed, with the input shaft IS.

In addition, the third, fourth, fifth, and sixth input gears DI3, DI4,DI5, and DI6 are disposed so as not to be directly affected by therotation of the input shaft IS (free gear), the third and fourth inputgears DI3 and DI4 are selectively connected to the input shaft ISthrough a second synchronizer mechanism SYN2, and the fifth and sixthinput gears DI5 and DI6 are selectively connected to the input shaft ISthrough a third synchronizer mechanism SYN3.

Therefore, the first, third, fourth, fifth, and sixth input gears DI1,DI3, DI4, DI5, and DI6 are selectively engaged with each sleeve S1, S2,and S3 provided at each of the first, second, and third synchronizermechanisms SYN1, SYN2, and SYN3 so as to rotate with the input shaft IS.

In addition, a first output gear OG1, a fourth synchronizer mechanismSYN4 having first and second speed gears DO1 and DO2 respectivelyengaged with the first and second input gears DI1 and DI2, and third,fourth, fifth, and sixth speed gears DO3, DO4, DO5, and DO6 respectivelyengaged with the third, fourth, fifth, and sixth input gears DI3, DI4,DI5, and DI6 are disposed on the output shaft OS.

The first and second speed gears DO1 and DO2 are disposed so as not todirectly affect rotation of the output shaft OS (free gear) and rotateswith the output shaft OS by selectively engagement with a sleeve S4 of afourth synchronizer mechanism SYN4. The third, fourth, fifth, and sixthspeed gears DO3, DO4, DO5, and DO6 are integrally formed, and may bemonolithically formed, with the output shaft OS

In addition, a second output gear OG2 and a fifth synchronizer mechanismSYN5 having a reverse speed gear RG engaged with the first speed gearDO1 are disposed on the reverse speed output shaft RS disposed inparallel with the input shaft IS.

The reverse speed gear RG is disposed so as not to directly affect onrotation of the reverse speed output shaft RS, and rotates with thereverse speed output shaft RS by selective engagement with a sleeve S5of a fifth synchronizer mechanism SYN5.

In addition, the first and second output gears OG1 and OG2 are engagedto a driven gear of a differential so as to output converted torque.

Since the first, second, third, fourth, and fifth synchronizermechanisms SYN1, SYN2, SYN3, SYN4, and SYN5 are the same as or similarto a synchronizer mechanism applied to a conventional manualtransmission, detailed description thereof will be omitted. In addition,each sleeve S1, S2, S3, S4, and S5 of the first, second, third, fourth,and fifth synchronizer mechanisms SYN1, SYN2, SYN3, SYN4, and SYN5, aswell known to a person of skill in the art, is operated by a shift forkthat is operated by a shift lever disposed at a driver's seat.

Power delivery paths of the manual transmission at each shift-speed willbe discussed.

The torque is output through the input shaft IS, the first input gearDI1, the first speed gear DO1, the output shaft OS, and the first outputgear OG1 at a first forward speed, is output through the input shaft IS,the second input gear DI2, the second speed gear DO2, the output shaftOS, and the first output gear OG1 at a second forward speed, is outputthrough the input shaft IS, the third input gear DI3, the third speedgear DO3, the output shaft OS, and the first output gear OG1 at a thirdforward speed, is output through the input shaft IS, the fourth inputgear DI4, the fourth speed gear DO4, the output shaft OS, and the firstoutput gear OG1 at a fourth forward speed, is output through the inputshaft IS, the fifth input gear DI5, the fifth speed gear DO5, the outputshaft OS, and the first output gear OG1 at a fifth forward speed, isoutput through the input shaft IS, the sixth input gear DI6, the sixthspeed gear DO6, the output shaft OS, and the first output gear OG1 at asixth forward speed, and is output through the input shaft IS, the firstinput gear DI1, the first speed gear DO1, the reverse speed gear RG, thereverse speed output shaft RS, and the second output gear OG2 at areverse speed.

In a manual transmission according to various embodiments of the presentinvention, the first input gear DI1 is not integrally formed with theinput shaft IS but is disposed as a free gear, and the firstsynchronizer mechanism SYN1 is used for connecting the first input gearDI1 with the input shaft IS.

In a case that the first synchronizer mechanism SYN1 is in a neutralstate, the torque of the input shaft IS is not delivered to the firstinput gear DI1 and the first speed gear DO1 and the reverse speed gearRG do not rotate. Therefore, occurrence of rattle due to rotationalinertia may be improved.

In a case of shifting to the first forward speed, however, the firstsynchronizer mechanism SYN1 and the fourth synchronizer mechanism SYN4are simultaneously operated. In a case of shifting to the reverse speed,the first synchronizer mechanism SYN1 and the fifth synchronizermechanism SYN5 are simultaneously operated.

Accordingly, at least five shift rails are necessary in a manualtransmission according to various embodiments of the present invention.Referring to FIG. 5, shift rails applied to a manual transmissionaccording to various embodiments of the present invention will bedescribed.

As shown in FIG. 5, a manual transmission according to variousembodiments of the present invention includes a first shift rail 10, asecond shift rail 20, a third shift rail 30, a fourth shift rail 40, anda fifth shift rail 50. The first, second, third, fourth, and fifth shiftrails 10, 20, 30, 40, and 50 are sequentially disposed from one side tothe other side.

Shift lugs 12, 32, 42, and 52 operated by a control finger is mounted onshift rails 10, 30, 40, and 50 except the second shift rail 20, andshift fork for operating the sleeves S5, S1, S4, S2, and S3 of thefifth, first, fourth, second, and third synchronizer mechanisms SYN5,SYN1, SYN4, SYN2, and SYN3 is disposed at each shift rail 10, 20, 30,40, and 50.

A control finger of the control shaft pushes a selected shift lug amongthe shift lugs 12, 32, 42, and 52 to an axial direction by control ofthe shift lever. Therefore, a shift fork disposed on a correspondingshift rail operates a corresponding sleeve so as to perform shifting.

If the sleeve S1 of the first synchronizer mechanism SYN1 is moved tothe left in the drawing and the sleeves S4 and S5 of the fourth andfifth synchronizer mechanisms SYN4 and SYN5 are moves to the right inthe drawing in the manual transmission according to various embodimentsof the present invention, shifting to the first forward speed or thereverse speed is performed. Therefore, when shifting to the firstforward speed or the reverse speed, the second shift rail 20 moves to anopposite direction of the first or third shift rail 10 and 30.

Accordingly, a synchronizer operating device shown in FIG. 5 to FIG. 7is disposed in the manual transmission according to various embodimentsof the present invention. The synchronizer operating device includesfirst and second rotation links 60 and 70 having band shape and anelastic member 80 pushing the second shift rail 20 to a neutralposition.

The first rotation link 60 connects the first shift rail 10 with thesecond shift rail 20, and a middle portion thereof is fixed to atransmission housing through a hinge 62.

In addition, one end portion of the first rotation link 60 (disposednear the first shift rail 10), as shown in FIG. 6, is provided with aslot 64 having a predetermined length along a length direction thereofsuch that a hinge protrusion 14 fixed to the first shift rail 10 isslidably inserted in the slot 64. In addition, the other end portion ofthe first rotation link 60 (disposed near the second shift rail 20) hasa side that is cut to a direction to which the sleeve S1 is moved so asto be engaged and the opposite side provided with a supporting portion66 so as to support a protrusion 22 fixed to the second shift rail 20.

The second rotation link 70 connects the third shift rail 30 with thesecond shift rail 20, and a middle portion thereof is fixed to thetransmission housing through a hinge 72.

One end portion of the second rotation link 70 (disposed near the secondshift rail 20), as shown in FIG. 7, has a side that is cut to adirection to which the sleeve S1 is moved so as to be engaged and theopposite side provided with a supporting portion 76 so as to support aprotrusion 24 fixed to the second shift rail 20. In addition, the otherend of the second rotation link 70 (disposed near the third shift rail30) is provided with a slot 74 having a predetermined length along alength direction thereof such that a hinge protrusion 34 fixed to thethird shift rail 30 is slidably inserted in the slot 64.

As shown in FIG. 8, the third shift rail 30 moves to the right in thedrawing in a case of shifting to the first forward speed. At this time,the second rotation link 70 rotates clockwise with respect to the hinge72 and pushes the second shift rail 20 to the left in the drawing.Therefore, the sleeves S1 and S4 of the first and fourth synchronizermechanisms SYN1 and SYN4 move to opposite directions of each other andshifting to the first forward speed is achieved.

In a case of shifting to a neutral state from the first forward speed,the third shift rail 30 is forcibly moved to the left in the drawing bythe control finger forming a shift control apparatus, and the secondshift rail 20 is moved to the right in the drawing by the elastic forceof the elastic member 80 and is returned to an original position thereof

In a case of shifting to the reverse speed, the first shift rail 10 ismoved to the right in the drawing, as shown in FIG. 9. At this time, thefirst rotation link 60 rotates anticlockwise with respect to the hinge62 and pushes the second shift rail 20 to the left in the drawing.Therefore, the sleeves S1 and S5 of the first and fifth synchronizermechanisms SYN1 and SYN5 move to opposite directions of each other andshifting to the reverse speed is achieved.

In a case of shifting to the neutral state from the reverse speed, thefirst shift rail 10 is forcibly moved to the left in the drawing by thecontrol finger forming the shift control apparatus, and the second shiftrail 20 is moved to the right in the drawing by the elastic force of theelastic member 80 and is returned to the original position thereof

In addition, the third shift rail 30 is operated in a case of shiftingto the second forward speed. At this time, if the third shift rail 30,as shown in FIG. 10, is moves to the left in the drawing, the secondrotation link 70 rotates anticlockwise with respect to the hinge 72.However, since the supporting portion 76 of the second rotation link 70does not push the protrusion 24 of the second shift rail 20, the secondshift rail 20 does not move and the shifting to the second forward speedis achieved.

As described above, the first input gear DI1 is not integrally formedwith the input shaft IS and is connected to the input shaft IS throughthe first synchronizer mechanism SYN1 according to various embodimentsof the present invention. Therefore, idling of the first input gear DI1,the first speed gear DO1, and the reverse speed gear RG is prevented atthe shift-speeds other than the first forward speed and the reversespeed.

Therefore, occurrence of rattle due to rotational inertia generated byidling of the first input gear DI1, the first speed gear DO1, and thereverse speed gear RG may be prevented.

For convenience in explanation and accurate definition in the appendedclaims, the terms front or rear, and etc. are used to describe featuresof the exemplary embodiments with reference to the positions of suchfeatures as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

1. A manual transmission for vehicles, comprising: an input shaft havingfirst, second, third, fourth, fifth, and sixth input gears disposedthereon; an output shaft disposed in parallel with the input shaft at apredetermined distance and having a first output gear and first, second,third, fourth, fifth, and sixth speed gears disposed thereon, the first,second, third, fourth, fifth, and sixth speed gears being respectivelyengaged with the first, second, third, fourth, fifth, and sixth inputgears; and a reverse speed output shaft disposed in parallel with theoutput shaft at a predetermined distance and having a second output gearand a reverse speed gear disposed thereon, the reverse speed gear beingengaged with the first speed gear; wherein the first input gear isselectively connected to the input shaft by a first synchronizermechanism; the second input gear is monolithically formed with the inputshaft; the third and fourth input gears are selectively connected to theinput shaft by a second synchronizer mechanism; the fifth and sixthinput gears are selectively connected to the input shaft by a thirdsynchronizer mechanism; the first and second speed gears are selectivelyconnected to the output shaft by a fourth synchronizer mechanism; thethird, fourth, fifth, and sixth speed gears are monolithically formedwith the output shaft, and the reverse speed gear is selectivelyconnected to the reverse speed output shaft by a fifth synchronizermechanism.
 2. The manual transmission of claim 1, further comprising: afirst shift rail operating the fifth synchronizer mechanism; a secondshift rail operating the first synchronizer mechanism; a third shiftrail operating the fourth synchronizer mechanism; a fourth shift railoperating the second synchronizer mechanism; and a fifth shift railoperating the third synchronizer mechanism.
 3. The manual transmissionof claim 2, wherein the first, second, third, fourth, and fifth shiftrails are sequentially disposed.
 4. The manual transmission of claim 2,wherein the first, third, fourth, and fifth shift rails are respectivelyprovided with a shift lug for moving a corresponding shift rail.
 5. Themanual transmission of claim 3, further comprising a synchronizeroperating device moving the second shift rail by a movement of the firstshift rail or the third shift rail.
 6. The manual transmission of claim5, wherein the synchronizer operating device comprises: a first rotationlink connecting the first shift rail with the second shift rail andmoving the second shift rail to an opposite direction of a movingdirection of the first shift rail when the fifth synchronizer mechanismis operated; and a second rotation link connecting the second shift railwith the third shift rail and moving the second shift rail to anopposite direction of a moving direction of the third shift rail whenthe fourth synchronizer mechanism is operated.
 7. The manualtransmission of claim 6, wherein the synchronizer operating devicefurther comprises an elastic member supplying elastic force forreturning the second shift rail moved by the movement of the first shiftrail or the third shift rail to an original position.
 8. The manualtransmission of claim 6, wherein the second rotation link is adapted tomove the second shift rail in a case the third shift rail moves to onedirection and not to move the second shift rail in a case that the thirdshift rail moves to the other direction.
 9. The manual transmission ofclaim 6, wherein the first rotation link is configured that the movementof the third shift rail is not affected by the movement of the firstshift rail.
 10. The manual transmission of claim 6, wherein the secondrotation link is configured that the movement of the first shift rail isnot affected by the movement of the third shift rail.
 11. A manualtransmission for vehicles in which a first input gear on an input shaftis engaged with a first speed gear on an output shaft and a reversespeed gear on a reverse speed output shaft is engaged with the firstspeed gear; wherein the first input gear is selectively connected to theinput shaft by a first synchronizer mechanism, and wherein the manualtransmission further comprises a synchronizer operating device thatoperates the first synchronizer mechanism by operations of a fourthsynchronizer mechanism and a fifth synchronizer mechanism.
 12. Themanual transmission of claim 11, wherein the synchronizer operatingdevice further comprises: a first rotation link interposed between afirst shift rail for operating the fifth synchronizer mechanism and asecond shift rail for operating the first synchronizer mechanism andadapted to push the second shift rail to an opposite direction of amoving direction of the first shift rail; a second rotation linkinterposed between a third shift rail for operating the fourthsynchronizer mechanism and the second shift rail for operating the firstsynchronizer mechanism and adapted to push the second shift rail to anopposite direction of a moving direction of the third shift rail; and anelastic member supplying elastic force to the second shift rail to anoriginal position.
 13. The manual transmission of claim 12, wherein thefirst rotation link has both end portions and a middle portion, andwherein the middle portion is hinged to a transmission housing, the oneend portion has a slot having a predetermined length along a lengthdirection thereof such that a hinge protrusion fixed to the first shiftrail is slidably inserted in the slot, and the other end portion has aside that is cut and the other side formed of a supporting portion forsupporting a protrusion fixed to the second shift rail.
 14. The manualtransmission of claim 12, wherein the second rotation link has both endportions and a middle portion, and wherein the middle portion is hingedto the transmission housing, the one end portion has a side that is cutand the other side formed of a supporting portion for supporting aprotrusion fixed to the second shift rail, and the other end portion hasa slot having a predetermined length along a length direction thereofsuch that a hinge protrusion fixed to the third shift rail is slidablyinserted in the slot.